Difficulties arise in drilling holes into and/or through a structure. This particularly occurs when a driller uses a hand held drill and a hole needs to be drilled into the structure such that the hole needs to remain within a relatively small tolerance of angular deviation from a desired orientation with respect to the surface of the structure. Often the desired orientation of the hole relative to the surface of the structure is perpendicular. Should the drilled hole deviate from the tolerance, the hole will result in positioning a fastener in an undesirable position relative to the surfaces of the structure. For example, a tightening of the fastener in a hole outside the tolerance of deviation from perpendicular will cause a head and/or tightening nut to exert an undesired uneven torque force onto the surface of the structure. To avoid this type of undesired result a drilled hole which exceeds the permitted tolerance will need to be reworked which results in higher costs and delays in fabrication.
Other conditions complicate drilling holes which need to comply with a small tolerance of angular deviation with respect to the surface of the structure being drilled. These conditions include drilling areas with little room to maneuver, are not well lit or are otherwise obstructed for drilling. These conditions, for example, arise in drilling holes in fabricating an aircraft such as within a wing. The tolerance of angular deviation from perpendicular is often targeted to be within two degrees (2°) and such surfaces of this structure are often slightly contoured. In other instances, outside that of fabricating an aircraft, conditions are can be further complicated. These conditions may include a hole needs to be drilled into and/or through a structure wherein the environment is potentially explosive and would require Class 1 Division 1 rated electronic devices that are explosion proof.
Current drill guides are often inadequate as a result of inaccessibility of the area or surface to be drilled. The drilling process in these instances is slowed. Drilling guides such as egg cups are unstable on small surfaces, would require custom designs for each hole to be drilled and may require the operator to have a free hand all of which slows the drilling process. Robotic drilling may be employed but is generally cost prohibitive. Opposite surface sensing/drilling equipment tends to be clumsy, faulty and slow in carrying out the drilling process.